금강 용담댐 하류의 어류군집 특성과 조사어구별 채집어종의 차이, 멸종위기어종의 서식양상을 밝히기 위해 2023년 5월부터 8월까지 족대와 투망, 일각망, 통발을 이용하여 5개 지점을 2회 조사하였다. 조사결과 11과 35종 2,010개체가 채집되었으며, 우점종은 참갈겨니(Zacco koreanus, 비교풍부도 30.1%), 아우점종은 돌고기(Pungtungia herzi, 11.9%), 그 다음으로 칼납자루(Acheilognathus koreensis, 8.6%), 긴몰개(Squalidus gracilis majimae, 7.4%), 눈동자개 (Pseudobagrus koreanus, 6.0%) 등의 순으로 우세하였다. 출현종 중 환경부지정 멸종위기야생생물은 I급의 감돌고기 (Pseudopungtungia nigra), II급의 돌상어(Gobiobotia brevibarba), 꺽저기(Coreoperca kawamebari) 등 3종이 출현하였고, 한국고유종은 칼납자루, 줄납자루(A. yamatsutae), 감돌고기, 쉬리(Coreoleuciscus splendidus), 참중고기(Sarcocheilichthys variegatus wakiyae), 긴몰개, 돌상어, 돌마자(Microphysogobio yaluensis), 참갈겨니, 참종개(Iksookimia koreensis), 눈동자 개, 금강자가사리(Liobagrus geumgangensis), 꺽지(C. herzi), 동사리(Odontobutis platycephala), 얼록동사리(O. interrupta) 등 15종(고유화율 42.9%)이, 외래어종은 생태계교란 생물로 지정된 배스(Micropterus salmoides)와 블루길(Lepomis macrochirus) 2종이 출현하였다. 군집분석 결과, 비교적 우점도(0.38~0.57)와 균등도(0.66~0.78)는 낮고 종 다양도 (2.01~2.52), 종 풍부도(2.98~3.94)는 높게 나타났다. 하천건강성평가(FAI)는 지점별 87.5~100.0으로 모두 매우좋음(A)으로 평가되었다. 어구별 출현결과를 보면 족대는 8과 23종 294개체, 투망은 6과 19종 627개체, 일각망은 8과 25종 824개체, 통발은 9과 20종 265개체로 나타나, 종수와 개체수는 일각망이 가장 높았고, 종수는 투망이, 개체수는 통발이 가장 적었다. 어구별 채집 특성을 보면, 투망은 표층성 유영어류가, 족대는 소형 저서성 어류가 많이 채집되었고 일각망은 종수와 개체수가 가장 풍부하게 채집된 어구이며, 통발은 이입어종인 꺽저기가 많이 채집되어 주목되었다. 출현 어류 중 멸종위기종 I급인 감돌고기는 비교적 안정적으로 서식하고 있었고, II급의 돌상어는 소수 서식이 확인되었으며, 꺽저기는 국내도입종으로 많은 개체가 서식하고 있어 주목되었다. 교란요인으로 조사기간 중 일부 구간이 하천공사로 어류 서식지가 교란되고 있었고, 생태계교란생물로 지정된 배스와 블루길이 각각 17개체 출현하여 우려되었다. 따라서 본 구간에서 안정적인 어류 서식을 위해서는 무분별한 하천공사는 지양해야 하고, 배스와 블루길의 개체수를 감소시킬 수 있는 구제방안이 필요하며, 최근 도입된 꺽저기의 서식범위 및 양상, 생태계에 미치는 영향 등에 대한 연구가 요구되었다.

LIn this study, we investigated the habitat characteristics of a Jeonju Duckjin lake in Jeonju City, Jeonbuk, in which a large group of reeve’s turtle(Mauremys reevesii)(endangered species Class II and natural monument No. 453 in Korea) was discovered. The lake where reeve’s turtle(M. reevesii) was discovered, was beside Jeonbuk National university. That lake was surrounded by lotuses, dam, and reeds. We found 12 reeve’s turtle(M. reevesii)(included with 2 juveniles), 30 red eared slider (Trachemys scripta elegans)(included with 4 juveniles), 22 river cooter(Pseudemys concinna)(included with 5 juveniles), and 6 Chinese stripe necked turtle(Mauremys sinensis)(included with 4 juveniles) from June to September, 2024, respectively. A number of red-eared sliders(Trachemys scripta elegans) which threaten the survival of reeve’s turtle(M. reevesii), were also found in and around the lake. Newborn turtles in this year were not observed. However, we estimated that natural breeding had sufficiently occurred since we observed many young turtles in the lake. Furthermore, the presence of young red-eared slider individuals can be a persistent problem for reeve’s turtle(M. reevesii) as they are competing species. In conclusion, in-situ conservation method should be considered for protecting the endangered turtle and their habitat.

This study evaluated the management priority of small catchments in the Nam River basin, comprehensively considering the impact of non-point pollution sources for water quality improvement. Water quality data from the Water Environment Measurement Network and additional field survey data were collected to understand the water quality status at the small catchment level. The management priority was calculated by integrating data on pollution sources, land cover, and runoff using a weighted method. As a result, the E08-2 small catchment, located downstream of the Nam River, showed the highest priority, followed by A18, B09, E04, and A19. The main factor influencing the water quality improvement priority was the pollution source characteristics within the small catchment, especially the influence factor and land use condition. This study contributes to the efficient water quality management of the Nam River basin by identifying the priority by small catchment through analysis that simultaneously considers point and non-point pollution sources.

This study investigated the occurrence and morphological characteristics of Polyphylla laticollis manchurica adults in the Miho River, Cheongju, from June to August 2024. Surveys were conducted at five sites along a 14 km stretch from upstream of Palgyeol Bridge to downstream of Oksan Bridge, including three sites along the main river and two sites in tributaries. No P. laticollis manchurica adults were found at the tributary sites. A total of 107 adults were recorded at site C and D, with peak occurrence observed between June 20 and August 4, 2024. The first occurrence date was recorded in June 20, the peak occurrence on July 5, and the last observation on August 4. The morphological measurements of the adults attracted by light trap were as follows: body length 33.38±1.68 mm; body width 16.02±1.00 mm; and body weight 1.45±0.32 g. The sex ratio (male : female) was 7.14 : 2.86. While no significant differences were observed in body length and width between males and females, females were significantly heavier during the third survey period. Most adults attracted to artificial light were males, and several dead individuals were found near streetlights and bridge. This study provides fundamental data on the occurrence period, habitat distribution, and phototactic behavior of P. l. manchurica, contributing to a better ecological understanding and conservation efforts for this endangered species.

This study analyzed the spatiotemporal changes of wetlands in the Saemangeum watershed by comparing topographic maps from the 1918 and 2015, and analyzed the changes in connectivity among wetland habitats through wetland network analysis. The results showed that wetlands that were widely distributed around rivers and estuaries in the past have been largely lost, while artificial reservoirs around agricultural lands have increased in the upper reaches. Although the wetland area including artificial reservoirs increased slightly, most of the natural wetlands around the river channel were lost, and the dominant wetland type and distribution in the watershed changed significantly. In particular, the connectivity between coastal wetlands and inland wetlands decreased and the connectivity around small reservoirs increased, resulting in a disconnection of the wetland network structure. These changes may have a negative impact on the movement of wetland organisms and the circulation of materials, and further affecting the stability of the Saemangeum watershed ecosystem. In order to restore wetland biodiversity in the Saemangeum watershed, it is necessary to restore the past wetland areas and monitor the remaining wetlands. It is urgent to establish resilient governance and develop a restoration plan to maintain connectivity among marine, freshwater, and terrestrial ecosystems.

This study investigated benthic macroinvertebrates and fish in the Yeongsangang River weir and analyzed stomach contents of Squalidus chankaensis tsuchigae. Length distribution of individuals varied by site, with 91.3% and 72.7% falling within the 70-90 mm range in SC-U (upstream location of Seungchon weir) and SJ (location between Seungchon and Juksan weirs), respectively, and 77.5% within 70-80 mm and 100 mm range in JS-D (downstream location of Juksan weir). Chironomidae spp. (nonred type) were the most abundant food sources, comprising 46.3%, 76.9%, and 88.3% of the diet at SC-U, SJ, and JS-D, respectively. The Electivity Index (EI) indicated a strong preference for Chironomidae spp. (non-red type) (0.927) and avoidance for the red type (-0.929) and Limnodrilus gotoi (-0.995). The proportion of burrowers (BU) increased downstream, while swimmers (SW) decreased. The condition factor (K) varied by site, decreasing in SC-U and increasing in SJ and JS-D, showing a significant positive influence on the number of food sources (p<0.05). Among food sources, Chironomidae spp. and Baetidae sp. were predicted to be utilized across a broad range of lengths and weights, with strong connectivity observed among Tanypodinae sp., Hymenoptera sp., and Baetiella tuberculata.

대규모 하천의 수량(river storage) 변동으로 인해 발생하는 지각 변형을 정량적으로 평가하기 위해, GNSS (Global Navigation Satellite System) 기반의 지각 변위 자료와 GRACE (Gravity Recovery and Climate Experiment) 인공위성 중력 자료, 그리고 WaterGAP 수리 모형 산출 자료를 종합적으로 분석하였다. 우리는 아마존 강 유역에 대해 수로에 집중되어 분포하는 하천 수량 변동을 선 형태의 하중으로 모형화하고, 이로부터 유발되는 지각의 탄성 변형을 계산해 GNSS 관측치와 비교하였다. 이를 통해, 이 지역에서 발생하는 계절적 지각 변위 중 하천 수량 변동에 기인하 는 성분을 선 하중 모형으로 성공적으로 설명할 수 있음을 확인하였다. 이러한 결과는 원격 탐사 자료를 활용해 대규 모 하천의 수량 변동을 추정할 수 있을 뿐 아니라, 이를 토대로 GRACE가 관측하는 육상 물 저장량(terrestrial water storage, TWS)에서 토양 수분이나 지하수 변동 등의 개별 요소를 분리 및 검증할 수 있는 방법론을 제시한다. 나아가, 본 연구에서 제안된 접근법은 기후 변화로 인한 수문학적 재해 예측과 수자원 관리 등 다양한 분야에서 더욱 정교한 해석과 활용을 가능하게 할 것으로 기대된다.

본 연구는 조류가 발생하는 낙동강에 위치한 정수장에서 남세균 및 마이크로시스틴(MC)을 분석하였다. 마이크로시스틴 분석을 위한 독소 추출 방법의 효과를 확인하였다. 정수처리 공정별로 취수원수, 착수정수, 전오존 처리수, 응집⋅침전 처리수, 여과 처리수, 정수의 수질을 분석한 결과, 탁도와 클로로필-a 농도는 공정 진행에 따라 크게 감소하며 남세균이 효과적으로 제거되었음을 확인하였다. 마이크로시스틴 분석을 위해 세포 내 독소 추출을 위한 초음파 처리, 동결/해동법, 메탄올 추출법을 비교한 결과, 동결/해동법이 가장 효과적인 것으로 나타났으며, 메탄올 추출법은 상대적으로 낮은 추출 효율을 보였다. 본 연구 수행 시 남세균이 충분히 발생하지 않아 모든 샘플에서 마이크로시스틴이 검출되지 않았다. 따라서 고농도 남세균 발생시 정수장 공정별 남세균 및 독소 농도에 대한 후속 연구가 반드시 필요하다고 생각된다. 정수처리공정은 남세균과 독소를 제거하는 데 있어서 가장 중요한 부분이며 공정에서의 남세균과 독소의 제거 능력을 정확히 분석하는 것이 중요하다.

This study investigated the distribution and growth performance of Bolboschoenus planiculmis under varying estuarine environmental conditions. We aimed to determine the optimal planting methods and environmental conditions with respect to salinity, soil texture, and tidal regimes on its growth performance. Our findings revealed a significant reduction in B. planiculmis coverage, shrinking to 955,393 m2 in 2024, representing only 38.59% of that compared to 2004. The plant’s survival rate exhibited a clear salinity gradient: 0 ppt (89±8.01%)>5 ppt (64±4.56%)>15 ppt (37±4.25%)>30 ppt (0±0.00%). Planting density significantly influenced growth, with 24 tubers m-2 yielding the highest number of plants per tuber (14.67±0.33). A planting depth of 5 cm proved optimal for tuber germination and growth. Soil texture analysis demonstrated that a lower sand content promoted growth, with the highest density observed in soil containing 10% sand (435±6.96 plants m-2). Tidal influence also played an important role, with areas experiencing regular tidal fluctuations fostering the most successful growth. Planting tubers or young plants with attached tubers in these tidal zones led to the highest survival rates and biomass.

Ecological indicators are tools used to evaluate the state of specific environments by monitoring the ecological characteristics and changes of organisms, and they are widely utilized in environmental monitoring and management. Such indicators should be sensitive to environmental changes, maintain long-term stability, and be easy to investigate and analyze. This study aimed to evaluate whether the spraint density of the Eurasian otter (Lutra lutra) can monitor the state and changes in river ecosystems. Using spraint density data over nine years (2014~2024), we analyzed temporal and spatial changes in otter distribution. Generalized Additive Models were applied to assess annual variability, and spatial clustering and distribution changes were examined using Hotspot Analysis and Geo-SOM (Geo-Self-Organizing Map). The results indicated stable spraint density trends in most sub-watersheds, with higher variability in developed areas. This study highlights the potential of spraint density as a cost-effective and simple ecoological indicator for long-term river ecosystem monitoring.

Fishways, particularly installed at the estuary, have a purpose to encourage fluent migration for migratory fishes, as well as amphidromous and even freshwater species. Not choosing the laborious traditional method of using traps, we assessed the efficiency of the two fishways installed at the west and east barrage of the Nakdong River estuarine barrage respectively, by analyzing the videos recorded through automatic monitoring system. We randomly selected 30 videos monthly at each fishways and identified what kind of fishes were using the fishways and categorised their behaviour such as size, time and whether they passed the monitoring system or not. As a result, a total 8 families 14 species were recorded by monitoring system, with the most dominance of Erythroculter erythropterus (Relative Abundance: 59.5%), followed by Micropterus salmoides (R.A: 19.9%) and Mugil cephalus (R.A: 9.9%). The monitoring system can capture passing fishes during night but the number of appearances of fish species at each hour of a day indicated significant diurnal activities (p<0.05). When fishes pass the monitoring system, approximately 70% of them passed through the monitoring device, while 17% of them showed fallback movement. Our finding indicates that species-specific characteristics of each fish are well represented through video monitoring method. In order to maximise advantages of using video monitoring, it is necessary to consider the installation point properly so that the monitoring system does not interfere with the movement of fish. Also, the utilisation of AI technology in the future is also necessary.

This study investigated fish communities at a total of 11 sites across four rivers in the region in 2005 and 2015. Sampling was conducted twice at each site using cast nets (10×10 mm mesh size) and scoop nets (4×4 mm and 5×5 mm mesh sizes). Basic water quality measurements and river naturalness assessments were also performed. Based on fish community survey results, a Self-Organizing Map (SOM) analysis was employed to evaluate the impact of urbanization on fish communities in the study area. The results revealed a tendency for decreased electrical conductivity in water quality and improved scores in river naturalness assessments. Compared to the environmental conditions in 2005, the overall naturalness of the study area appeared to have increased by 2015. A total of 721 individual fish representing 32 species from 12 families were collected. The dominant species was largemouth bass (Micropterus salmoides, 141 individuals, 19.6%), and the subdominant species was dark chub (Zacco temmincki, 132 individuals, 18.3%). The SOM analysis demonstrated a clear distinction in fish community distribution patterns between the survey years. Brackish water species such as Plecoglossus altivelis, Lateolabrax japonicus, and Mugil cephalus, along with introduced species like Erythroculter erythropterus, exhibited higher frequencies in 2015. Although the occurrence of exotic species tended to decrease compared to 2005, the presence of bluegill (Lepomis macrochirus) showed an increase in 2015. These findings suggest an increase in species favoring deeper waters and lacustrine environments, with notable growth in populations of introduced and exotic species.

This study investigated the annual change and distribution of flora, including endangered species, Korean Red List species, and invasive plants, in the Nakdong River Estuary Ecological Park over a 10-year period (2013~2023). The park was established in 2009 as part of the Four Major Rivers Restoration Project. The investigation identified a total of 704 taxa, comprising 137 families, 401 genera, 631 species, 18 subspecies, 38 varieties, 11 forms, and 6 hybrids. Eulsukdo Ecological Park exhibited the highest plant diversity with 531 taxa, followed by Hwamyeong (404 taxa), Samnak (387 taxa), Daejeo (369 taxa), and Maekdo (356 taxa). The endangered wildlife survey identified three endangered plant species (Class II): Euryale ferox, Brasenia schreberi, and Saururus chinensis. Following the endangered species restoration project, E. ferox has been consistently observed both within the restoration area and the riparian of main channel. The Urbanization Index (UI) was highest in Eulsukdo Ecological Park (24.1%), followed by Hwamyeong (20.0%), Samnak (18.1%), Maekdo (17.8%), and Daejeo Ecological Parks (16.7%). Twelve invasive plants were identified: Sicyos angulatus, Lactuca scariola, Ambrosia trifida, Ambrosia artemisiifolia, Solanum carolinense, Aster pilosus, Hypochaeris radicata, Rumex acetosella, S. altissima, Paspalum disticum, Paspalum distichum var. indutum, and Humulus japonicus. Notably, S. altissima showed a significant decrease in its total distribution area, shrinking from 741,092 m2 in 2021 to 241,396 m2 in 2024. Continuous monitoring and management are necessary to prevent invasive plants, including ecosystem-disturbing species, from forming large colonies and hindering the growth of native plants.

This study employed text mining techniques to analyze the major topics and research trends in plant ecological studies conducted in the Nakdong River basin. A total of 131 research articles published between 1977 and 2023 were collected from domestic and international academic databases. Our analysis revealed that the primary research themes include: wetland plant management and restoration, regional flora investigation, the relationship between aquatic plant communities and water quality, wetland plant community structure and distribution, riparian vegetation, and Phragmites australis (common reed). The majority of these studies were based on short-term field surveys (less than one year in duration; 79.7%), with a focus on regional flora investigation (30.5%), vegetation mapping (21.4%), and plant growth characteristics (17.6%). To ensure the longterm sustainability of the Nakdong River ecosystem, we suggest prioritizing long-term ecological research (LTER) initiatives and incorporating diverse research approaches, such as mesocosm experiments that manipulate key environmental factors. This comprehensive approach to plant ecological research will be crucial for evaluating the stability and resilience of the Nakdong River ecosystem and will ultimately contribute to the development of robust, scientifically informed decision-making processes and management strategies.

This study investigated the long-term dynamics of phytoplankton communities, key environmental factors, and indicator species in Mulgeum, a major downstream site of the Nakdong River, from 1993 to 2020. Monthly phytoplankton densities ranged from 189 to 52,757,982 cells mL-1, with diatoms dominating yearround (29.1~93.4%). Notably, cyanobacteria exhibited the highest growth rates, which could exacerbate algal blooms under long-term climate change. Using generalized additive models, five environmental factorsdissolved oxygen, transparency, total phosphorus, phosphate, and discharge-were found to significantly influence monthly variations in most taxa. Cyanobacteria were most sensitive to environmental changes, while chrysophytes showed minimal dependence on specific factors. Principal component analysis grouped environmental conditions into five clusters, with each cluster characterized by distinct conditions and indicator species. A total of 122 species were identified as indicators, with green algae contributing the most. Cluster 1, characterized by high transparency and low phosphorus, was dominated by Stephanodiscus hantzschii, a common species in eutrophic waters. Cluster 4, associated with high phosphorus, highlighted Cyclotella ocellata as a key indicator, emphasizing phosphorus as a crucial determinant for diatom structure. These findings underscore the critical role of hydrological and nutrient factors in shaping phytoplankton communities and provide insights into ecological responses to environmental changes in the Nakdong River system. The results can inform sustainable management strategies to mitigate eutrophication.

This study used text mining to analyze public interest and research trends related to the Nakdong River. We examined news articles (1990~2024) and academic publications (1960~2024) to understand the evolving relationship between societal concerns and scientific research. Main findings reveal growing public interest towards the Nakdong River, with initial focus on pollution related to the industrial development shifting to large-scale river modification projects and water quality issues. This increased awareness mirrored trends in research, where early emphasis on classic ecology and water quality expanded to include sociocultural, educational aspects and advanced methodologies. The study highlights a dynamic interplay between public discourse and scientific inquiry, with research priorities aligning with societal concerns like water pollution, algal blooms, and biodiversity loss, underscoring the need for integrated, multidisciplinary research that addresses emerging environmental challenges and promotes sustainable management of the Nakdong River ecosystem under climate change and other societal shifts.

This study summarizes the history of zooplankton research in the Nakdong River basin, Korea, and discusses its main characteristics by topic. A review of major academic search portals revealed 56 studies on zooplankton in the Nakdong River basin, which account for 27.6% of the 203 domestic freshwater zooplankton studies. With the exception of one study conducted before the construction of the estuary barrage, all other research was carried out after the barrage was built. Of the studies, 27 were related to lotic ecosystems, and 29 focused on lentic ecosystems, with research predominantly conducted south of Daegu Metropolitan City. Short-term studies of less than a year were common for lentic ecosystems, while longterm studies were mainly focused on lotic ecosystems. The key research sites were the Mulgeum water intake in the lower Nakdong River and Upo Wetland, the largest inland wetland in Korea, where research periods and zooplankton sampling were most diverse. Research on predation and prey interactions has been ongoing, as zooplankton plays an intermediary role by feeding on phytoplankton and serving as food for juvenile fish. Recent studies show that, since around 2015, the water quality and zooplankton community dynamics around Mulgeum have changed, requiring continuous monitoring. To address this, predictive model analysis, isotope analysis, and indicator analysis, widely used in Nakdong River research, could help develop health indicators for aquatic ecosystems using zooplankton.

The Hangang River, serving as the primary water supply source for the capital region of South Korea, plays a vital role in sustaining regional ecosystems and ensuring water quality. Phytoplankton are integral to the maintenance of aquatic ecosystems and function as bioindicators of water contamination; however, the species-level composition and environmental interactions of phytoplankton in the Hangang River remain inadequately characterized. This study investigated the phytoplankton communities within the Hangang River system across eight sampling stations over eight sampling events from May 2021 to March 2022. A total of 71 species were identified, yielding a density of 3,560 cells mL-1, with Bacillariophyceae (36 species, 2,809 cells mL-1), Chlorophyceae (24 species, 212 cells mL-1), and Cyanophyceae (5 species, 394 cells mL-1) identified as the dominant groups. The most abundant species was Aulacoseira granulata (1,616 cells mL-1, 45.4%), followed by Stephanodiscus hantzschii (420 cells mL-1, 11.8%) and Phormidium tenue (383 cells mL-1, 10.8%). Spatial similarity analysis of the phytoplankton communities revealed three distinct groups: Group A (stations 1-4, upstream), Group B (stations 5-7, midstream), and Group C (station 8, downstream). Seasonal similarity analysis further categorized the communities into three groups: Group A (May, July, August, and October 2021), Group B (November and December 2021), and Group C (February and March 2022). These findings contribute to a deeper understanding of the spatial and seasonal dynamics of phytoplankton in the Hangang River system.

This study investigated the spatial distribution of dissolved organic carbon and the changes in tidal flat soil characteristics following the flooding season in the closed estuary of the Geumgang River basin. We found that after the flooding season, a brackish water area expanded due to increased river discharge, which also introduced low concentrations of dissolved organic carbon from the river. Dissolved inorganic carbon predominantly originated from the sea in proportion to salinity, indicating that in the closed estuary area, dissolved carbon supplied from the sea remained a significant source even after the flooding season. Additionally, a substantial amount of tidally transported silt and clay was deposited near the estuary dam after the flood, and its effects continued to influence the sediment characteristics downstream in the intertidal zone. As an empirical study in the closed estuary, our results are expected to contribute to conservation measures for the World Heritage Site in the area.